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An analysis of the propulsion and powering options for LNG carriers

Ekanem Attah, Effiong; (2021) An analysis of the propulsion and powering options for LNG carriers. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

The work presented in this thesis provides a comprehensive analysis of the propulsion and powering options for future LNGCs (Liquid Natural Gas Carriers) using academic methods and operational measurements. An analytical study of the LNGC fleet using the EEDI methodology was used initially from which it was concluded that the legislated performance requirements of the current EEDI protocol is insufficient to stimulate the design improvements needed to reduce the CO2 footprint of the LNGC fleet. The research further demonstrated that multiple baselines for different LNGC propulsion technologies would yield improved reductions of CO2 more compatible with the long term IMO (International Maritime Organisation) goal of reducing CO2 emissions by 50%. The issue of methane slip was also considered in the analysis because it has an impact on propulsion efficiency and the knowledge that methane is also a greenhouse gas. A method of calculating methane slip was developed to be included in proposed modified EEDI calculations revealing the need to ensure a holistic approach to atmospheric emissions impact is needed. Using modelling and simulation methods, case studies were undertaken to explore improvements to the current designs. Furthermore, when a comparative analysis of the different modern designs and upgraded options were carried out, it was seen that modern DFDE (dual fuel diesel engine) designs showed the highest efficiency and operational flexibility of the various options, due to its flexibility in the use of multiple prime movers which increases the reliability of these engines. By analysing the operational data carried out during practical case studies on-board LNGCs, it was determined that the operational profile differs markedly from the design profiles often presented in the literature. Sea trials conditions were found to be non-representative of realistic operational conditions hence the research focused on identifying methods where trial profiling could be better used to predict actual performance. Finally, the research also highlighted the specific operational safety practices carried out by ship operators which reduce the efficiency of the vessel below the design point and identified tested methods to reduce inefficiencies in these practices.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: An analysis of the propulsion and powering options for LNG carriers
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
URI: https://discovery.ucl.ac.uk/id/eprint/10119327
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